This invention relates to a scroll compressor wherein the non-orbiting scroll is of the type that moves axially for a limited distance. In the inventive embodiments, a separator plate which has typically been placed between the base of the non-orbiting scroll and an outer end cap is eliminated.
Scroll compressors are becoming widely utilized in refrigerant compression applications. In a standard scroll compressor, a first scroll has a base and a generally spiral wrap extending from the base. A second scroll has a base and a generally spiral wrap interfitting with the base of the first scroll. A second scroll is driven to orbit relative to the first scroll. Typically, one of the first and second scrolls must move axially to be held in engagement with the other scroll. A refrigerant is entrapped between the wraps of the two scrolls and compressed as the second scroll orbits relative to the first. The entrapped refrigerant creates a force tending to move the two scrolls away from each other. Thus, a portion of the compressed fluid is tapped behind the base of one of the two scrolls to resist this so-called separating force. In one common type of scroll compressor, the first scroll receives the tapped compressed fluid, and is allowed to move for a limited axial distance.
Typically, scroll compressors are enclosed in a sealed compressor housing. In such sealed compressor housings, a center shell receives an end cap which defines a fluid tight chamber. A separator plate defines a discharge pressure chamber. A separator plate defines a discharge pressure chamber on one side and a suction pressure chamber on the other side. Suction pressure fluid is allowed to enter the compressor housing through the center shell, and communicate with an area around a motor, cooling the motor. The separator plate performs the function of separating the interior of the housing into the discharge and suction pressure chambers.
It would be desirable to simplify the number of components in the above discussed scroll compressor.
In a disclosed embodiment of this invention, an axially movable non-orbiting scroll in a scroll compressor also separates the interior of the housing into the suction and discharge pressure chambers. In this way, the requirement of a separate separator plate is eliminated.
With the elimination of the separate separator plate, the base of the non-orbiting scroll includes a sealing member which seals with an inner surface of an end cap. In one embodiment, the seal defines the suction chamber outwardly of the seal, and a discharge chamber inwardly of the seal. With such an arrangement, the volume of the discharge pressure chamber is reduced compared to the prior art. This might result in increased discharge pressure pulsation. Thus, several modifications are utilized to increase the volume. In one, the end cap is domed outwardly to increase the volume of the discharge pressure chamber radially inwardly of the seal. In other embodiments, while the volume may not be increased, the pressure pulsations from the discharge chamber are reduced through any one of several features. As one example, a torturous path may be provided for the discharge pressure flow. In another embodiment, the base of the discharge pressure chamber may be cut away to increase the volume. In yet another embodiment, a Helmholtz resonator is utilized to lower the magnitude of the discharge pressure pulsation. In other embodiments, a discharge muffler may be mounted outwardly of the housing, thus lowering the necessary volume inside the housing.
In another embodiment of this invention, at least a large portion of the base of the non-orbiting scroll sees the discharge pressure itself on an opposed face from the compression chambers, the separating force is actually no longer merely overcoming the force of the refrigerant. Instead, the discharge pressure applies a force to the non-orbiting scroll member towards the orbiting scroll members at a level exceeding the separating force. Thus, a back pressure chamber is utilized to resist this excess discharge pressure. In a preferred embodiment a portion of the compressed refrigerant is tapped to a chamber defined by a pair of seals within a crankcase. This back pressure chamber resists the force from the discharge pressure chamber, and is combined with the separating force to maintain the orbiting and non-orbiting scroll members in proper position relative to each other.
In other features of this invention, various methods and arrangements for connecting the end cap to the center shell are disclosed. In the past, the separating plate has typically been incorporated into this connection. With the elimination of the separator plate, other structures must be utilized.
These and other features of the present invention can be best understood from the following specification and drawings, the following of which is a brief description.